DTM Creation

[Pamela]

I am attepting to build a dtm model of an existing site for which I downloaded survey data points. I have been able to successfully use these points to build existing dtm models in the past, but now I want to learn more about modeling as we are progressing from simple 2d plans to 3d presentations.

My first question - when I select the stake objects to build a dtm the contours extend past the perimeter boundary of the survey, I have tried adding 2d & 3d polys to the surface, and adding site modifier fences to force the contours to clip at the edge with no avail. I know this can be done, but can't get VW to work for me, any help would be appreciated.

Second question - What do all of the options in the site modifer object properties dialog box mean?

specifically the fence properties

say I select fence for the config option

what value do I enter for elevation and slope? I have a fence surrounding my site which varies by 30 feet of elevation from one end to the other, but not in a constant fashion. I have gone through the online help info to no avail, can someone please either give me answers or point me in the right direction to find them?

[dspearman]

before you create the dtm draw the poly to set the limits of the visible portion of the dtm. Then select both the poly and the survey points.

Alternatively, select the already created site model and use the menu command "Edit Group" you may then draw a poly setting the limits. Exit group and the site model should show its limits.

I think of the fence as the limit of influence of other site modifiers. Another way of thinking of it is as a limit of grading line. With a fence the elevation and slope values are irrelevant. In fact if you select a fence and look at the object info pallet they are not shown.

Elevation and slope parameters relate to the pad configuration for a site modifier.

[Pamela]

Tremendously helpful,

Thank you